The subject matter disclosed herein relates to flow meters and fluid metering technology with particular discussion about embodiments of an encoder device for use on gas meters, wherein one or more of the embodiments have particular utility to generate information that relates to flow of fluids through the gas meter.
Gas meters are a special type of flow meter that are configured to measure a volume of fluid. Utilities often employ gas meters to monitor supply of fuel gas (e.g., natural gas, propane, etc.) for various applications including applications that measure supply of gas to residential, commercial, and industrial consumers. In conventional designs, gas meters incorporate mechanical components that move in response to flow of the gas through one or more chambers of fixed size. Diaphragm-style gas meters, for example, use a diaphragm (or bellows) that continuously reciprocates in response to flow of the gas. The diaphragm actuates a mechanical linkage that translates the reciprocating motion to other movement (e.g., rotation) to turn dials and/or like indicators that provide visual indication (and/or quantification) of gas the consumer uses over time. Use of this mechanical structure in the design to measure the supply accounts for changes in properties of gases, which are particularly sensitive to deviations in temperature, pressure, and like operating conditions.
In addition to the functional constraints of gases, regulations can also influence the design and operation of gas meters. For example, certain regulations may require gas meters to have separate compartments, one each to keep the diaphragm(s) and related measurement structure (also “metrology” structure) separate from the dials (or “application” structure). Other regulations may specify that the metrology structure must operate independent from other parts of the gas meter, e.g., the application structure. More often, regulations also dictate that the compartment for the metrology structure must remain free from leaks of supply gas.
These requirements can add significant complexity to the design of the gas meter. Use of the mechanical structure, while offering accurate and repeatable measurement of supply, can allow supply gas to leak from the compartments because the mechanical linkage, which couples the metrology structure with the application structure, must extend across both of the compartments to properly convey the measured supply of gas to the dials. On the other hand, requirements for independent operation of the metrology structure can pre-empt designs that use the application structure or a unitary housing to seal the gas meter.